In power amplifiers, especially monolithic microwave integrated circuits (MMIC) power amplifiers, many amplifier devices, such as field effect transistors (FETs), may be combined in parallel to achieve high radio frequency (RF) power levels. RF signals are divided at the FET inputs and combined at the FET outputs. The output power of such MMIC FET power amplifiers is related to the number of FET devices in the amplifier--higher power amplifiers requiring more FETs. More FETs typically have required a larger MMIC die size due to the arrangement of the FETs on the die and requirements of the combiner and divider networks. However, larger MMIC die are more expensive as cost is approximately proportional to die size. Smaller MMIC die size is more desirable because of reduced cost, improved manufacturing and space requirements.
Amplifier technologies have been proposed to reduce space, such as that disclosed by Tserng (U.S. Pat. No. 5,519,358). However in Tserng, symmetric dividers and combiners can not be employed to allow even mode operation of the transistors, especially at high microwave frequencies.
Thus what is needed is a MMIC power amplifier that uses less die area. What is also needed is a power amplifier that may be manufactured for a lower cost. What is also needed is MMIC power amplifier that allows more FETs on the MMIC die. What is also needed is MMIC power amplifier that allows even mode operation of the FETs while reducing size and cost. What is also needed is a low cost, high gain, high efficiency microwave and millimeter wave frequency power amplifier suitable for use in commercial satellite, mobile communication and consumer products.